Brazil's president, Dilma Rousseff, who called in cabinet ministers to discuss the issue of NSA spying on Brazilians. Photograph: Ueslei Marcelino/Reuters

Brazil has called on Washington to explain why US intelligence agencies have been monitoring millions of emails and phone calls from its citizens, as the international fallout from the US whistleblower Edward Snowden's revelations spread to Latin America.

The foreign minister, Antonio Patriota, expressed "deep concern" about a report that appeared in O Globo newspaper at the weekend, which detailed how the US National Security Agency (NSA) had conducted extensive spying activities in Brazil.

Based on documents provided by Snowden, the O Globo story showed how the US had been carrying out covert surveillance on ostensibly friendly nations. Similar reports in Europe and Hong Kong have sparked indignation in recent weeks.

After the Brazilian president, Dilma Rousseff, called in cabinet ministers to discuss the issue, the government issued a statement of concern.

"The Brazilian government has asked for clarifications through the US embassy in Brasília and the Brazilian embassy in Washington," Patriota said. He said his country would ask the United Nations to work on an international regulation "to impede abuses and protect the privacy" of internet users.

The federal police and the Brazilian Telecommunications Agency have been instructed to investigate how the data is collected by the US spy agency.

The communications minister, Paulo Bernardo, said it was likely to have been done by satellite or by tapping undersea cables, but he also wanted to find out whether domestic international providers were involved.

"If that has happened, these companies broke Brazilian law and acted against our constitution, which safeguards the right to privacy," Bernardo said.

The O Globo story, which was written with the Guardian journalist Glenn Greenwald, sparked consternation in Brazil on Saturday when it pointed to surveillance maps among Snowden's documents that showed the country was among the most heavily data-mined nations, alongside China, Russia and Pakistan.

It showed the acquisition of data was done through the NSA's Fairview programme, which is a collaboration with an unnamed US telecommunications company to gain access to data flowing through its network.

"There are many more populations of non-adversarial countries which have been subjected to the same type of mass surveillance net by the NSA: indeed, the list of those which haven't been are shorter than those which have," he wrote.

He said Brazil was just an example of indiscriminate worldwide surveillance by the US.

Latin America is already bristling after the forced diversion last week of the Bolivian president Evo Morales's plane, which was denied access to Spanish, French, Italian and Portuguese airspace en route back from Moscow because of suspicions that Snowden was on board. It is assumed that the US was behind this policing action.

Snowden has not been seen or heard of in public since he landed at Moscow airport two weeks ago on his way from Hong Kong to Ecuador. However, WikiLeaks has issued statements on his behalf in which he revealed he had requested asylum in 26 countries.

Cuba's president, Raúl Castro, added his support for Snowden at the weekend. "We support the sovereign right of Venezuela and all states in the region to grant asylum to those persecuted for their ideals or their struggles for democratic rights," he told Cuba's national assembly. However, Cuba has yet to formally offer sanctuary to the former NSA contractor.

The Russian government has yet to comment on the asylum offers, but a senior parliamentarian indicated that patience may be running thin with Snowden, who has been living in the transit area of Moscow airport.

"Venezuela is waiting for an answer from Snowden. This, perhaps, is his last chance to receive political asylum," Pushkov said in a tweet on Sunday.

Although Snowden now has options in Latin America, his ability to travel there from Moscow is uncertain given the difficulty of crossing airspace in Europe and the possibility of any plane he is on being intercepted if it passes through US airspace.

Senior US politicians have underscored that any nation helping Snowden should suffer the consequences.

The US House intelligence committee chairman, Mike Rogers, said on Sunday that the US should look at trade agreements with the nations that are offering asylum "to send a very clear message that we won't put up with this kind of behaviour".

As the latest report from Brazil shows, documents provided by Snowden have contained embarrassing revelations about US spying operations on friendly nations as well as its own people.

The chairman of the joint chiefs of staff, General Martin Dempsey, said in a CNN interview on Sunday that US relations with some allies had been damaged and the revelations had affected "the importance of trust".

Dempsey said the US would "work our way back. But it has set us back temporarily."